Extrude Manifold making extra vertices
An easy way to get rid of a random vertex in the middle of an edge.
Select the offending vert and double tap G to do a vertex slide.  Move it all the way over to where it is in the same position as one of the vertices on the end.  Enable x-ray view and box select both of the vertices and do a Mesh -&gt; Merge -&gt; By Distance.
Extrude Manifold doesn't automatically generate good topology, unfortunately.  You have several faces here with more than 4 verts even getting rid of those two extra vertices.